Can I extend h1b if I change employer?

I moved to US on 1st of October 2014 (date when H1B petition was approved). So currently I am working about 6 month with Employer A.

Now I am going to make transfer for my H1B and work with Employer B.

The question is: Will I be able to apply for 3 years extension for my H1B in 2017 with Employer B?

Yes, when H1B is transferred to company B, the company may file for 3yrs.
If after 1yr you switch to company C, they can file for 3yrs too.

Rinse and repeat till you are well under 6yrs of H1B.

As a side note, if you already have H1B stamped from Company A, and your H1B is now held by a Company B, you don’t need to get H1B stamped if you travel back before your stamped H1B expires, even though it says petitioner is Company A